Conductivity relaxation parameters of some Ag + conducting tellurite glasses containing AgI or the (AgI) 0.75 (T1I) 0.25 eutectic mixture

Abstract

The conductivity relaxation parameters of some Ag + conducting tellurite glasses containing either AgI or the (AgI) 0.75-(T1I) 0.25 eutectic mixture have been determined from an analysis of ac conductivity data measured in a wide temperature range. Transport properties in these materials appear as due to an Ag + ion hopping mechanism. The stretched exponential function exp-( t/τ σ) β has been used to describe the conductivity relaxation. The relaxation parameters have been investigated as a function of the AgI rate. The results obtained are shown to be in good agreement with the predictions of the Ngai coupling model. A correlation has been also established for the glasses investigated between the stretched exponent β of conductivity relaxation function with the decoupling index R τ( T g), proposed by Angell, where R τ( T g) is the τ s/τ σ ratio of the average structural and conductivity relaxation times at the glass transition temperature T g.